This invention relates to metal salts of 1,2,4-thiadiazole that are especially effective as additives in lubricants that enable the lubricants to withstand extremely high pressure and yet maintain antiwear properties. This invention also comprehends lubricant compositions containing the metal salts.
Copper and zinc salts of 2,5-dimercapto-1,3,4-thiadiazole for use as complexing agents were reported in the Indian Journal of Chemistry, 1975, Vol. 13 (7), at pages 697 to 701 (CA83; 107518r). U.S. Pat. No. 4,136,043 (Davis) teaches a composition prepared by reacting dimercaptothiadiazoles with an oil soluble dispersant which are used for suppression of copper activity and "lead paint" decomposition in lubricants. U.S. Pat. No. 4,183,816 discloses the use of 2,4-di(lower alkyl)-1,2,4-thiadiazolidin-3,5-diones as ashless load carrying additives for functional fluids. U.S. Pat. No. 4,188,299 teaches the additive prepared by reacting 2,5-dimercapto-1,3,4-thiadiazole thiophosphoric acid with an alkaline earth metal neutralization agent which additive is used as oil additives to enhance anticorrosion, antioxidant, and antiwear properties. U.S. Pat. Nos. 1,304,537, 3,821,236 and 3,904,619 disclose disulfides of 1,2,4-thiadiazoles. None of the above mentioned prior art teaches the instant invention.
Many lubricants which are satisfactory for ordinary lubricating applications do not provide adequate protection under extremely heavy load conditions, such as metal deformation, cutting and grinding, gear lubrication of heavy duty machinery, and bearing lubrication under severe conditions. Present lubricants made for these purposes include sulfurized and chlorinated hydrocarbon oils and oils containing such additives as molybdenum disulfide, tungsten sulfides, heavy metal salts of dialkyldithiocarbamic acids, heavy metal salts of dialkyldithiophosphoric acids, polymers of mercapto thiadiazoles and organic and inorganic lead compounds.